A wood speaker box special purpose exempt primer polyurea coating

Abstract

The application discloses a wood sound box special purpose polyurea coating without primer. The polyurea coating comprises A component and B component, raw materials of the A component contain the following components with the mass percentage: 60-75% of polyisocyanate, 25-40% of polyether (ester) alcohol resin. The B component contains the following components with the mass percentage: 45-55% of polyether (ester) alcohol resin, 25-35% of amine chain extender, 5-8% of self-heat color filler, 3-5% of molecular sieve, 3-5% of piezoelectric ceramic micro powder, 1-3% of hollow glass microbead, 1-2% of leveling agent, 0.5-1% of wetting agent, 0.5-1% of silane coupling agent, 0.1-0.5% of catalyst and 0.1-0.3% of defoaming agent. The application can effectively improve the problem of water and other gas rapid overflow, reduce the phenomenon of pinhole and shrinkage, and improve the sound quality of the sound box.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of special coating for sound box, in particular to a wood sound box special primer-free polyurea material. BACKGROUND

[0002] Compared with plastic sound box, the wood sound box has the advantages of high density and better playback effect. The material of the sound box affects the performance of the sound box. The greater the density of the material of the sound box shell, the smaller the vibration of the box body when the sound is emitted, especially for active sound boxes with high-power amplifiers. In this way, the sound can be more real and low to restore to the original sound. The density of wood is much larger than that of plastic. Therefore, high-quality sound boxes are all wood structures.

[0003] However, wood is composed of cellulose and a small amount of gum, resin, pigment, tannin, etc. Although the amount of gum, resin, pigment, tannin, etc. is small, it has a great negative impact on the performance of the coating (mainly film-forming property and durability). It can affect the adhesion of the coating, and if it seeps upwards, it can also affect the appearance of the coating film. The wood fibers in the wood are hydrophilic, hygroscopic, and easy to expand and shrink, which can cause cracking and deformation. In the process of continuous moisture absorption and drying, wood is prone to cracking and deformation. In addition, if the hydrophobicity of the wood surface coating is not good, water will penetrate into the coating film during the coating and use process, which will affect the appearance, and in severe cases, it will accelerate the expansion and deformation of the wood fibers and rot.

[0004] At present, the common wood sound box coating is mostly water-based paint. For water-based paint, its environmental protection characteristics make it popular, but in the field of wood sound box application, due to its hydrophilic structure, it has poor durability; at the same time, the strength of the coating film itself is not enough, which is easy to scratch and fall off in the actual process.

[0005] Polyurea elastomer is a new environmentally friendly coating. The structure of polyurea coating has rigidity and toughness. It can effectively isolate the penetration of moisture and oxygen in the air due to its dense and jointless surface characteristics, and has excellent corrosion and waterproof effects. In addition, the plasticity of the coating itself is high, which can be adjusted by adjusting the resin structure and adding functional additives and other means, and can be endowed with functions such as aging resistance and high temperature resistance. In the field of sound box, it can improve the sound quality of the sound box by adding functional additives and fillers.

[0006] Although the wood is pretreated when the polyurea is applied on the surface of the wooden speaker box, some water remains in the substrate, and if the polyurea system is directly sprayed, the water remaining in the wood will rapidly evaporate through the nearly closed elastic resin layer from the bottom layer to the surface of the coating layer due to the rapid reaction and intense heat release of the polyurea system. The defects caused by the failure to escape result in pinhole-like small holes after drying, so the polyurea generally needs to be matched with a primer when applied on the surface of the wooden speaker box to perform hole sealing treatment on the surface of the wooden speaker box, thereby reducing the occurrence of pinhole problems during the polyurea spraying process and avoiding affecting the aesthetics of the coating layer and subsequent use problems.

[0007] In addition to the pinhole problem, the polyurea is often used on the surface of the wooden speaker box and some shrinkage holes are often generated. The shrinkage holes on the surface of the coating film are caused by the surface tension gradient, and the fluid flows from the low surface tension place to the high surface tension place due to the change of the composition of the coating and the temperature change, thereby forming a depression on the surface of the fluid. The viscosity, thixotropy, drying speed of the coating and the thickness of the coating film can intensify or weaken the flow ability of the coating fluid, thereby intensifying or weakening the degree of shrinkage. When designing the structure of the polyurea coating layer, these conditions need to be considered to reduce the generation of the shrinkage phenomenon under the premise of ensuring the functionality of the coating layer.

[0008] Therefore, it is necessary to provide an improved polyurea coating material without primer for wooden speaker boxes to solve the above problems. SUMMARY

[0009] The application provides a polyurea coating material without primer for wooden speaker boxes to solve the pinhole and shrinkage hole problems that are easily generated when the polyurea material is used on the surface of the wooden speaker box, improve the service life and aesthetics of the coating layer on the surface of the wooden speaker box, and simplify the construction steps and improve the construction efficiency.

[0010] The application provides a polyurea material without primer for wooden speaker boxes, which comprises components A and B, wherein;

[0011] The raw materials of the component A are matched in the following mass percentage: 60-75% of polyisocyanate, 25-40% of polyether polyol and / or polyester polyol;

[0012] The raw materials of the component B are matched in the following mass percentage: 45-55% of polyether polyol and / or polyester polyol, 25-35% of amine chain extender, 5-8% of self-heat color filler, 3-5% of molecular sieve, 3-5% of piezoelectric ceramic micro powder, 1-3% of hollow glass microbead, 1-2% of leveling agent, 0.5-1% of wetting agent, 0.5-1% of silane coupling agent, 0.1-0.5% of catalyst and 0.1-0.3% of defoaming agent.

[0013] Preferably, the polyisocyanate in the A component is one or more of 4,4'-MDI, 2,4'-MDI, 2,2'-MDI, PAPI, IPDI, HMDI.

[0014] Preferably, the polyether polyol and / or polyester polyol in the A, B components is one or more of polytetrahydrofuran diol, polyacrylate polyol, polybutadiene polyol, polyoxypropylene diol, polycarbonate diol, with a molecular weight distribution in the range of 250-6000.

[0015] Preferably, the amine chain extender in the B component is one or more of isophorone diamine, methyldiethanolamine, diethyltoluene diamine, dimethylthio toluene diamine.

[0016] Preferably, the self-heat color filler in the B component is one or more of magnesium oxide, aluminum oxide, boron nitride, high thermal conductivity carbon powder, titanium white powder, carbon black powder, iron yellow paste, lemon yellow paste.

[0017] Preferably, the hollow glass microbead in the B component is one or more of K15, K20, K25 models in 3M hollow glass microbead.

[0018] Preferably, the preparation method of the piezoelectric ceramic micro powder in the B component comprises:

[0019] A piezoelectric ceramic micro powder of perovskite type is synthesized by a hydrothermal method using lead nitrate and titanium tetrachloride as raw materials, with a particle size ≤0.6um.

[0020] Preferably, the leveling agent in the B component is one or more of silicone polymers or acrylate polymers.

[0021] Preferably, the wetting agent in the B component is one or more of polysiloxane, organofluorine modified polymer.

[0022] Preferably, to promote the compatibility of inorganic fillers with the system, the silane coupling agent is one or more of γ-(2,3-epoxypropoxy) propyl trimethoxysilane, 3-glycidyl propyl trimethyl siloxane, aniline methyl triethoxysiloxane.

[0023] Preferably, the catalyst is one or more of dibutyl tin dimetasilicate, stannous octoate, dibutyl tin diacetate, bismuth isooctoate.

[0024] Preferably, the defoaming agent is one or more of fluorine-modified silicone defoaming agent or acrylic defoaming agent. The defoaming agent and other functional additives with good compatibility with the system and moderate molecular weight are used to ensure that the system maintains appropriate viscosity and thixotropy, which is more helpful to effectively reduce the phenomenon of pinholes and shrinkage without the aid of primer.

[0025] The beneficial effects of the present application are as follows:

[0026] 1、The present application realizes the gradient exothermic of the system by introducing different activity isocyanate and gradient reaction with chain extender, which can effectively improve the problem of rapid overflow of water vapor and other gases caused by wood surface defects due to the violent exothermic reaction of the coating; hollow glass beads and a certain fraction of piezoelectric ceramic particles are added to the polyurea coating, which improves the absorption intensity of the coating to sound waves at a specific frequency through the combination of piezoelectric active dissipation and acoustic wave scattering dissipation, and has a frequency range with large absorption intensity, effectively improving the sound quality of the sound box.

[0027] 2、The polyurea material provided by the present application also has excellent physical properties, zero VCC, good wear resistance and low temperature flexibility, etc.

[0028] 3、The polyurea material provided by the present application can reach tensile strength ≥22MPa, elongation at break ≥200%, tear strength ≥65N / mm, wear resistance ≤20mg, adhesion ≥4MPa; the coating on the surface of the sound box wood board substrate is dense without pinholes and shrinkage under naked eye observation, and the material itself is safe, environmentally friendly and non-polluting, which meets the export environmental protection requirements while ensuring that the sound box adapts to different outdoor use scenarios. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0030] The present application provides a wood sound box special primer-free polyurea material, which comprises A and B components, and the raw materials of the A component are proportioned as follows according to mass percentage:

[0031] 60-75% of polyisocyanate, 25-40% of polyether (ester) polyol:

[0032] The raw materials of the B component are proportioned as follows according to mass percentage:

[0033] 45-55% of polyether (ester) polyol resin, 25-35% of amine chain extender, 5-8% of self-heat color filler, 3-5% of molecular sieve, 3-5% of piezoelectric ceramic powder, 1-3% of hollow glass beads, 1-2% of leveling agent, 0.5-1% of wetting agent, 0.5-1% of silane coupling agent, 0.1-0.5% of catalyst, and 0.1-0.3% of defoaming agent.

[0034] In the present application, the A component contains 60-75% by mass of polyisocyanate, which in the embodiments of the present application can be specifically 60%, 62%, 64%, 66%, 68%, 70%, 73% or 75%. In the present application, the polyisocyanate is one or more of 4,4'-MDI, 2,4'-MDI, 2,2'-MDI, PAPI, IPDI, HMDI; preferably 4,4'-MDI and PAPI, preferably in a mass ratio of 3:1.

[0035] In the present application, the A component contains 25-40% by mass of polyether (ester) polyol, which in the embodiments of the present application can be specifically 25%, 27%, 29%, 31%, 33%, 37% or 40%. In the present application, the polyether alcohol resin is one or more of polytetrahydrofuran diol, polyacrylate polyol, polybutadiene polyol, polypropylene oxide diol, polycarbonate diol, preferably polypropylene oxide diol.

[0036] In the present application, the B component contains 45-55% by mass of polyether alcohol resin, which in the embodiments of the present application can be specifically 35%, 36%, 37%, 38%, 39% or 40%. In the present application, the polyether (ester) polyol resin is one or more of polytetrahydrofuran diol, polyacrylate polyol, polybutadiene polyol, polypropylene oxide diol, polycarbonate diol, one or more of which has a number average molecular weight distribution in the range of 250-6000, preferably polyether (ester) polyol with a molecular weight of 2000-6000.

[0037] In the present application, the preparation method of the A component comprises: stirring and heating the polyether polyol in an inert environment to 100-120°C, vacuum negative pressure dehydration, adding isocyanate when the system is cooled to 55-65°C, and reacting at 85-95°C for 2-2.5h to obtain the A component, which has an NCO content of 18-21%.

[0038] In the present application, the B component contains 25-35% by mass of amine chain extender, which in the embodiments of the present application can be specifically 15%, 17%, 19%, 21%, 23% or 25%. In the present application, the amine chain extender is one or more of isophorone diamine, methyldiethanolamine, diethyltoluene diamine, dimethylthio toluene diamine; when two, preferably diethyltoluene diamine and dimethylthio toluene diamine, in a mass ratio of 2:1; when three, preferably isophorone diamine, diethyltoluene diamine and dimethylthio toluene diamine, in a mass ratio of 1:2:1.

[0039] In the present application, the B component includes self-heat color filler with mass fraction of 5% to 8%, which can be specifically 5%, 6%, 7% or 8% in the embodiments of the present application. In the present application, the self-heat filler is one or more of magnesium oxide, aluminum oxide, boron nitride, high-thermal-conductivity carbon powder, titanium white powder, carbon black powder, iron yellow slurry and lemon yellow slurry, preferably boron nitride, high-thermal-conductivity carbon powder, carbon black powder and titanium white powder.

[0040] In the present application, the B component includes molecular sieve with mass fraction of 3% to 5%, which can be specifically 3%, 4% or 5% in the embodiments of the present application, and the specification is 3A.

[0041] In the present application, the B component includes hollow glass microbeads with mass fraction of 1% to 3%, which can be specifically 1%, 1.5%, 2%, 2.5% or 3% in the embodiments of the present application. In the present application, the hollow glass microbeads are one or more of K15, K20 and K25 types of 3M hollow glass microbeads, preferably K15 and K20, and the mass ratio is preferably 1:2.

[0042] In the present application, the B component includes piezoelectric ceramic micro powder with mass fraction of 3% to 5%, which can be specifically 3%, 4% or 5% in the embodiments of the present application.

[0043] In the present application, the preparation method of the piezoelectric ceramic micro powder includes (the following embodiment is prepared by using this method):

[0044] Perovskite type piezoelectric ceramic micro powder is synthesized by using lead nitrate and titanium tetrachloride as raw materials by a hydrothermal method, and the particle size is ≤0.6um.

[0045] In the hydrothermal synthesis method, lead nitrate is dissolved in deionized water in a reaction kettle; titanium tetrachloride is hydrolyzed and precipitated in KOH aqueous solution, heated to near boiling, and then added to the reaction kettle after filtration and washing of the precipitate; then a certain amount of KOH is added and stirred uniformly, and the reaction kettle is sealed and placed in a heating furnace for reaction.

[0046] The reaction temperature of the hydrothermal synthesis is preferably 150-200℃, and more preferably 200℃.

[0047] The reaction time of the hydrothermal synthesis is 20-80min, which can be specifically 20, 40, 60 or 80min in the embodiments of the present application, and is preferably 40min.

[0048] After the hydrothermal synthesis reaction is completed, the reaction kettle is taken out and cooled to room temperature, the container is opened and the precipitate is taken out, filtered, and the mother liquor is collected and then washed, precipitated, dried and crushed for standby use.

[0049] In the present application, the B component contains 1% to 2% of a leveling agent by mass fraction, which in the embodiments of the present application can be specifically 1%, 1.5% or 2%. In the present application, the leveling agent is one or several of silicone polymer or acrylate polymer, preferably acrylate BYK-S706.

[0050] In the present application, the B component contains 0.5% to 1% of a wetting agent by mass fraction, which in the embodiments of the present application can be specifically 0.5% or 1%. In the present application, the wetting agent is one or more of polysiloxane, organofluorine modified polymer, preferably organofluorine modified polymer.

[0051] In the present application, in order to promote the compatibility of inorganic fillers with the system, the B component contains 0.5% to 1% of a silane coupling agent by mass fraction, which in the embodiments of the present application can be specifically 0.5% or 1%. In the present application, the silane coupling agent is one or more of γ-(2,3-epoxypropoxy) propyl trimethoxysilane, 3-glycidoxypropyl trimethyl siloxane, aniline methyl triethoxysiloxane, preferably 3-glycidoxypropyl trimethyl siloxane, aniline methyl triethoxysiloxane, with a mass ratio of 1:1.

[0052] In the present application, the B component contains 0.1% to 0.5% of a catalyst by mass fraction, which in the specific embodiments of the present application can be specifically 0.1%, 0.25% or 0.5%. In the present application, the catalyst is one or more of dibutyl tin dimetasilicate, stannous octoate, dibutyl tin diacetate, bismuth isooctoate, zinc isooctoate, preferably bismuth isooctoate.

[0053] In the present application, the B component contains 0.1% to 0.3% of an antifoaming agent by mass fraction, which in the specific embodiments of the present application can be specifically 0.1%, 0.2% or 0.3%. In the present application, the antifoaming agent is one or more of fluorine-modified silicone antifoaming agent or acrylic antifoaming agent, preferably fluorine-modified silicone antifoaming agent.

[0054] In the present application, the preparation method of the B component preferably comprises: stirring and dispersing the polyether alcohol resin, amine chain extender, self-heat color filler, molecular sieve, piezoelectric ceramic micro powder, hollow glass microbead, leveling agent, wetting agent, silane coupling agent and catalyst uniformly, and then adding antifoaming agent to continue dispersing uniformly to obtain the B component. In the present application, the stirring speed before adding the antifoaming agent is preferably 800 to 1100 r / min, which in the embodiments can be specifically 800, 900, 1000 or 1100 r / min; the stirring speed after adding the antifoaming agent is preferably 500 to 700 r / min, which in the embodiments can be specifically 500, 600 or 700 r / min.

[0055] In the present application, the wood speaker special purpose bottom-free polyurea coating forms a functional coating after spraying, and the volume ratio of the A component and the B component is preferably 1:1.

[0056] The wood speaker special purpose bottom-free polyurea material provided by the present application is further described in the following examples, but they should not be considered as limiting the protection scope of the present application.

[0057] Example 1

[0058] A wood speaker special purpose bottom-free polyurea coating is composed of A and B components, wherein the A component comprises 30 parts of polyoxypropylene glycol with a molecular weight of 2000, 50 parts of 4,4'-MDI, and 20 parts of PAPI.

[0059] The B component comprises 45 parts of polyoxypropylene glycol with an average molecular weight of 4000, 22 parts of diethyl toluene diamine, 11 parts of dimethylthio toluene diamine, 2 parts of boron nitride, 1 part of high-thermal-conductivity carbon powder, 1.5 parts of carbon black powder, 1 part of titanium white powder, 5 parts of molecular sieve, 5 parts of piezoelectric ceramic micro powder, 2 parts of 3M hollow glass microbead K15, 1 part of 3M hollow glass microbead K20, 1 part of BYK-S706, 1 part of organic fluorine modified polymer, 0.7 parts of γ-(2,3-epoxypropoxy) propyl trimethoxysilane, 0.5 parts of bismuth isooctoate, and 0.3% of fluorine modified silicone defoaming agent.

[0060] Preparation of the A component: under inert conditions, the polyether polyol is heated to 100-120℃ under stirring in an inert environment, vacuum negative pressure dehydration (<-0.1 MPa), and when the system is cooled to 55-65℃, 4,4'-MDI is added, and after reaction at 85-95℃ for 1-1.5 h, PAPI is added to prepare the A component.

[0061] Preparation of the B component: the polyoxypropylene glycol, diethyl toluene diamine, dimethylthio toluene diamine, boron nitride, high-thermal-conductivity carbon powder, carbon black powder, titanium white powder, molecular sieve, piezoelectric ceramic micro powder, 3M hollow glass microbead K15, K20, BYK-S706, organic fluorine modified polymer, γ-(2,3-epoxypropoxy) propyl trimethoxysilane, and bismuth isooctoate are stirred at a speed of 1000 r / min for 0.5 h, and then the fluorine modified silicone defoaming agent is added and stirred at a speed of 600 r / min for 10 min to prepare the B component.

[0062] The A and B components are sprayed on the surface of the wood speaker and PP plate at a volume ratio of 1:1.

[0063] Example 2

[0064] A wood speaker special primer-free polyurea coating is composed of two components A and B, wherein the component A comprises 30 parts of polyoxypropylene glycol with a molecular weight of 4000, 45 parts of 4,4'-MDI and 25 parts of PAPI.

[0065] The component B comprises 46 parts of polyoxypropylene glycol with a molecular weight of 4000, 22 parts of diethyl toluene diamine, 11 parts of dimethylthio toluene diamine, 2 parts of boron nitride, 1 part of high thermal conductivity carbon powder, 2 parts of carbon black powder, 1 part of titanium white powder, 5 parts of molecular sieve, 5 parts of piezoelectric ceramic micro powder, 1 part of 3M hollow glass microbead K15, 0.5 part of 3M hollow glass microbead K20, 1 part of BYK-S706, 1 part of organic fluorine modified polymer, 0.4 part of 3-glycidyloxypropyl trimethyl siloxane, 0.4 part of aniline methyl triethoxysiloxane, 0.4 part of bismuth isooctoate and 0.3% of fluorine modified silicone defoaming agent.

[0066] Preparation of the component A: under inert condition, the polyether polyol is heated to 100-120℃ under stirring in inert environment, vacuum negative pressure dehydration (<-0.1MPa), when the system is cooled to 55-65℃, 4,4'-MDI is added, after reaction at 85-95℃ for 1-1.5h, PAPI is added to prepare the component A.

[0067] Preparation of the component B: the polyoxypropylene glycol, diethyl toluene diamine, dimethylthio toluene diamine, boron nitride, high thermal conductivity carbon powder, carbon black powder, titanium white powder, molecular sieve, piezoelectric ceramic micro powder, 3M hollow glass microbead K15, K20, BYK-S706, organic fluorine modified polymer, γ-(2,3-epoxypropoxy) propyl trimethoxysilane, aniline methyl triethoxysiloxane and bismuth isooctoate are stirred at a speed of 1000r / min for 0.5h, then the fluorine modified silicone defoaming agent is added and stirred at a speed of 600r / min for 10min to prepare the component B.

[0068] The components A and B are sprayed on the surface of wood speaker and PP plate at a volume ratio of 1:1.

[0069] Example 3

[0070] A wood speaker special primer-free polyurea coating, which is different from example 1 in that the component A comprises 30 parts of polyoxypropylene glycol with a molecular weight of 4000 and 70 parts of 4,4'-MDI. The other aspects are the same as example 1, which will not be repeated here.

[0071] Example 4

[0072] A wood speaker special purpose primer-free polyurea coating, which is different from example 1, the B component includes: 45 parts of polyoxypropylene glycol with an average molecular weight of 4000, 22 parts of diethyl toluene diamine, 11 parts of dimethylthio toluene diamine, 2 parts of boron nitride, 1 part of high thermal conductivity carbon powder, 1.5 parts of carbon black powder, 1 part of titanium white powder, 5 parts of molecular sieve, 5 parts of piezoelectric ceramic micro powder, 3 parts of 3M hollow glass microbead K15, 1 part of BYK-S706, 1 part of organic fluorine modified polymer, 0.7 parts of gamma-(2,3-epoxy propoxy) propyl trimethoxysilane, 0.5 parts of bismuth isooctanoate, 0.3% of fluorine modified silicone defoaming agent. The others are the same as example 1, which will not be repeated here.

[0073] Comparative example 1

[0074] A wood speaker special purpose primer-free polyurea coating, which is different from example 1, the B component includes: 45 parts of polyoxypropylene glycol with an average molecular weight of 4000, 22 parts of diethyl toluene diamine, 11 parts of dimethylthio toluene diamine, 2 parts of boron nitride, 5 parts of molecular sieve, 5 parts of piezoelectric ceramic micro powder, 2 parts of 3M hollow glass microbead K15, 1 part of 3M hollow glass microbead K20, 1 part of BYK-S706, 1 part of organic fluorine modified polymer, 0.7 parts of gamma-(2,3-epoxy propoxy) propyl trimethoxysilane, 0.5 parts of bismuth isooctanoate, 0.3% of fluorine modified silicone defoaming agent.

[0075] Comparative example 2

[0076] A wood speaker special purpose primer-free polyurea coating, which is different from example 1,

[0077] The B component includes: 45 parts of polyoxypropylene glycol with an average molecular weight of 4000, 22 parts of diethyl toluene diamine, 11 parts of dimethylthio toluene diamine, 2 parts of boron nitride, 1 part of high thermal conductivity carbon powder, 1.5 parts of carbon black powder, 1 part of titanium white powder, 5 parts of molecular sieve, 1 part of piezoelectric ceramic micro powder, 2 parts of 3M hollow glass microbead K15, 1 part of 3M hollow glass microbead K20, 1 part of BYK-S706, 1 part of organic fluorine modified polymer, 0.7 parts of gamma-(2,3-epoxy propoxy) propyl trimethoxysilane, 0.5 parts of bismuth isooctanoate, 0.3% of fluorine modified silicone defoaming agent.

[0078] The present application carries out aesthetic evaluation on the above-mentioned example prepared speaker, and carries out performance test on the material, and the results are shown in table 1 (a wood speaker spraying polyurea material 0# on the market is compared).

[0079] Table 1 performance test results

[0080]

[0081]

[0082] As shown in Table 1, Examples 1# to 4# and Comparative Example 2#, compared to Competitor 0#, showed virtually no pinholes or shrinkage cavities when sprayed onto the wooden speaker substrate. Furthermore, the mechanical properties, hardness, toughness, and adhesion of the materials were significantly improved compared to the competitor. However, due to the reduced content of self-absorbing filler in Comparative Example 1#, the overall suppression effect on the exothermic reaction of the coating was weakened to some extent, resulting in a small number of pinholes appearing on the speaker surface.

[0083] This invention uses professional audio signal generator software to perform sine wave testing (1000 Hz), low frequency testing (30-60 Hz), and high frequency testing (5000-8000 Hz) on the above-mentioned Examples 1# to 4#, Comparative Examples 1# to 2#, and Competitor 0#. The results are shown in Table 2.

[0084] Table 2 Sound quality test results

[0085]

[0086] As shown in Table 2, Examples 1# to 4# and Comparative Example 1# showed improved sound quality compared to Competitor 0#, especially in the bass and midrange frequencies, where the improvement was significant. However, due to the significantly reduced piezoelectric ceramic content in Comparative Example 2#, the improvement in sound quality was greatly reduced.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A primer-free polyurea coating for wood materials, characterized in that, It includes component A and component B. The raw materials of component A include, by mass percentage: 60% to 75% polyisocyanate, 25% to 40% polyether polyol and / or polyester polyol; the polyisocyanate is 4,4'-MDI and PAPI. The raw materials of component B, by mass percentage, include: 45%–55% polyether polyol and / or polyester polyol, 25%–35% amine chain extender, 5%–8% self-heating filler, 3%–5% molecular sieve, 3%–5% piezoelectric ceramic micro powder, 1%–3% hollow glass microspheres, 1%–2% leveling agent, 0.5%–1% wetting agent, 0.5%–1% silane coupling agent, 0.1%–0.5% catalyst, and 0.1%–0.3% defoamer; The self-absorbing heat filler is boron nitride, high thermal conductivity carbon powder, titanium dioxide and carbon black powder; the volume ratio of component A to component B is 1:(0.9~1.1).

2. The polyurea coating according to claim 1, characterized in that, The polyether polyols and / or polyester polyols in components A and B are one or more of polytetrahydrofuran diol, polyacrylate polyol, polybutadiene polyol, polyoxypropylene diol, and polycarbonate diol. And / or, the amine chain extender in component B is one or more of isophorone diamine, methyl diethanolamine, diethyltoluene diamine, and dimethylthiotoluene diamine.

3. The polyurea coating according to claim 1, characterized in that, The hollow glass microspheres in component B are one or more of the K15, K20, and K25 models of 3M hollow glass microspheres.

4. The polyurea coating according to claim 3, characterized in that, The hollow glass microspheres in component B are K15 and K20 from 3M hollow glass microspheres.

5. The polyurea coating according to any one of claims 1-4, characterized in that, The piezoelectric ceramic micropowder in component B is prepared as follows: perovskite-type piezoelectric ceramic micropowder with a particle size ≤0.6um is synthesized by hydrothermal method using lead nitrate and titanium tetrachloride as raw materials.

6. The polyurea coating according to any one of claims 1-4, characterized in that, The preparation method of component A includes: stirring and heating polyether polyol and / or polyester polyol in an inert environment to 100-120°C, dehydrating under vacuum negative pressure, adding polyisocyanate when the system cools down to 55-65°C, and reacting at 85-95°C for 2-2.5 hours to obtain component A.

7. The polyurea coating according to any one of claims 1-4, characterized in that, The preparation method of component B includes: stirring and dispersing polyether polyol and / or polyester polyol, amine chain extender, self-heating pigment and filler, molecular sieve, piezoelectric ceramic micro powder, hollow glass microspheres, leveling agent, wetting agent, silane coupling agent and catalyst evenly, and then adding defoamer and continuing to disperse evenly to obtain component B.

8. The polyurea coating according to claim 7, characterized in that, The leveling agent in component B is one or more of organosilicon polymers or acrylate polymers; And / or, the wetting agent in component B is one or more of polysiloxane and organofluorine modified polymer; the silane coupling agent is one or more of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-glycidoxypropyltrimethylsiloxane, and anilinemethyltriethoxysilane.

9. The polyurea coating according to claim 7, characterized in that, The catalyst is one or more of dibutyltin disilicate, stannous octanoate, dibutyltin diacetate, and bismuth isooctanoate; The defoamer is one or more of a fluorine-modified silicone defoamer or an acrylic defoamer.

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